strange shower electrics problem

[dbini]

hello - i've got a weird problem with the shower - the RCD trips when the shower is off, and the isolator pullswitch is off. sometimes at the same time as the pullswitch is turned off usually a few minutes later.
its a protek b32 RCD, and looks newer than the rest of the RCDs in the panel. (rented house - not sure of the history)
i've replaced the pullswitch, but the problem seems to be getting worse. its a 10.5kw shower that i put in just over a year ago to replace the existing one that stopped working. it only started tripping a couple of months ago.

i think its strange that it doesn't happen when switching on, or during a shower, but after everything's switched off - does anybody have any ideas what might have gone wrong? and is it dangerous?

cheers, john

 

[scottyboyiow]

Just to clarify, is it definatly a B32 'RCD'? Does it have a test switch button on it with 30mA written on it somewhere? Or is it a B32 MCB?

 

[dbini]

its an MCB

 

[scottyboyiow]

If you have now installed a 10.5kW shower (although you put it in a year ago), this will need upgrading to a 40A mcb. However this can only be done if the cable supplying the shower is big enough. It's probably best to get a sparks to come out and have a look. Has the shower got an ECO setting? Setting the shower down to ECO might stop the MCB tripping until it is sorted.

 

[dbini]

cheers man,

but i'm still confused as to why it happens when its isolated...

 

[scottyboyiow]

I was assuming that the shower had just been in use when the MCB tripped? Or a few minutes after? A sparks will be able to test the cable to let you know if you have another sort of fault. Have recently adjusted the power on the shower?

 

[ban-all-sheds]

its a 10.5kw shower that i put in just over a year ago to replace the existing one that stopped working.

Why on earth did you put a 10.5kW load on a 32A breaker?

Is your landlord happy with the idea of an ignorant and dangerous fool fiddling with his electrical installation?

 

[dbini]

the shower i took out was a 10.5kw - i thought it best to go with something the same

 

[ban-all-sheds]

You didn't realise it was wrong?

 

[dbini]

no - apparently it had been in for 6 years with no problem until the switch broke

 

[ban-all-sheds]

Like I said, ignorant and therefore dangerous and therefore a fool to be fiddling with things you don't understand.

And your landlord is a bigger fool to allow you.

 

[dbini]

i'm guessing the landlord put the original shower in himself. and i'm an idiot for not checking everything before replacing it.

so let me get this straight - on a 32a circuit, the shower should be no more than 7kW.
i need to get an electrician in to assess the wiring, to see whether its the right rating to upgrade the MCB, otherwise replace the shower with a less powerful model.

whichever way, its going to cost the landlord, but make the whole thing safer.

 

[scottyboyiow]

Thats right mate, 7.5kW is your maximum you should have on it. Speak to your landlord and get a sparks in to see what you can have! As I said before if it has an ECO option, turn it to that until you have it sorted.